Effect of air pollution on leaf morphology in narrow-leafed ash (Fraxinus rotundifolia Mill.), oriental plane (Platanus orientalis L.) and box elder (Acer negundo L.) (Case study: Urmia city)

The increasing amount of air pollutants in large cities has turned into a crucial factor that affects morphological and physiological tree characteristics, particularly on leaf level. In order to study those effects, 5 areas ranging from least to most polluted areas were initially selected in Urmia, the capital of West Azerbaijan province, using fixed and mobile air pollution recording stations of the Environment Office in August 2013. From each three species in each area 5 individuals were randomly selected and the leaves were measured in terms of their length of petiole, length of blade, maximum width of blade and leaf area. The above-mentioned parameters were repeatedly measured in May 2014. The ANOVA, Duncan and paired-t tests were performed analyze the data. The results revealed that the morphological properties of all species are affected by air pollutions (α = 0.05), with the greater effects occurred in August 2013 compared to May 2014.